Proteinase K is used in digestion of proteins from brain tissue samples for prions in Transmissible Spongiform Encephalopathies (TSE) research. Useful for the proteolytic inactivation of nucleases during the isolation of DNA and RNA, as well as in removal of endotoxins bound to cationic proteins such as lysozyme and ribonuclease A and in determination of enzyme localization on membranes.